This invention relates to a vehicle, such as a mass transit bus, and particularly to an engine configuration for the vehicle including the location, arrangement and support of various components of the engine for convenience of operation and maintenance.
The present invention is particularly but not exclusively directed to a system which uses drive communication components which are generally known as a xe2x80x9cseries hybridxe2x80x9d in which an internal combustion engine is associated with an electric generator such that operation of the engine is used to generate electric power rather than to provide direct power transmission to the vehicle. The electrical power is transmitted to an electric motor separate from the engine and connected to the ground wheels of the bus for driving the ground wheels and thus propelling the bus. Battery packs are provided for storing energy from the generator and from re-generated braking energy.
Another type of hybrid drive is the parallel hybrid in which the engine has a direct mechanical connection through a transmission to the drive wheels but is assisted by a motor/generator in parallel to the engine.
However the present invention is not wholly concerned with the series hybrid drive system but can also be used in conjunction with conventional drive systems having an internal combustion engine in which the drive communication component comprises a power transmission which communicates power from the engine through a mechanical or hydraulic linkage to the vehicle wheels.
Hybrid power vehicles have been proposed for many years but have recently received added attention in view of significant energy savings and reduction in emissions.
One example of a series hybrid system of this type proposed by Lockheed Martin and entitled HybriDrive(trademark) propulsion system is described in a brochure published by that company.
Another example is described in a paper issued by ISE Research Corporation of San Diego Calif. which describes initial trials using a drive system of this type.
In addition the components for the system including an engine control system, an electric generator for driving by the internal combustion engine, an electric drive motor and electric control systems has been developed by Allison Electric Drives which is a division of General Motors. These components therefore are available commercially but the arrangement, mounting and location of the elements in the vehicle is the responsibility and function of the vehicle manufacturer, bearing in mind the framing arrangements, structural elements and final drive components of the vehicle that they intend to manufacture.
One aspect of the present invention is therefore concerned with the layout, mounting and support of the various engine components for a vehicle and primarily for a transit bus.
The engine components either of the conventional construction or of the hybrid construction are conventionally mounted in the rear engine compartment of the bus so that they are accessible under rear cover for service. Conventionally the engine components are mounted on frame elements forming rigid components of the structure of the vehicle so that the installation of the engine components is carried out by installing one at a time within the engine compartment thus building up the complete engine structure on the vehicle itself.
Generally the frame of the vehicle includes two longitudinal frame beams spaced either side of the centre line of the vehicle and at the rear the beams include a coupling section inclined downwardly and rearwardly so that the portions of the beams on which the engine component sit are at a height downwardly from the frame beams forwardly of that point which pass over the rear axle. Various transverse members and tabs are provided on the beams so as to provide support for the various components of the engine as they are installed.
This method of installation in which the engine components are installed separately within the engine compartment has become widely adopted in the industry.
An alternative arrangement for mounting the engine components is to provide an entirely separate subframe assembly which can be installed into the engine compartment with the components already attached to the frame and carried thereby. This arrangement of course has the advantage that the engine components can be assembled separately from the vehicle in an area which can allow increased accessibility therefore allowing easier and faster work by the installers.
However this arrangement has the disadvantage that the frame itself carrying the engine components must be a self supporting frame with sufficient strength and rigidity to carry the components while they are transferred from the installation location into the engine compartment. This arrangement therefore increases the framing components required and provides excess strength and duplication of strengthening elements thus significantly increasing the weight and complexity of the total frame structure. This technique has therefore been generally abandoned in recent manufacturing systems, bearing in mind the high priority in current manufacturing techniques for minimizing cost and complexity by eliminating duplication.
It is one object of the present invention, therefore, to provide an improved layout and mounting of engine components for a vehicle to improve ergonomics and operation efficiency.
According to a first aspect of the invention there is provided a combination comprising:
a vehicle having:
a vehicle body including structural members therein;
a plurality of ground wheels mounted on the vehicle body for carrying the vehicle body in movement across the ground;
an engine system including a plurality of engine components for driving at least two of the ground wheels for propulsion of the vehicle;
a sub-frame for carrying at least some of the engine components;
the sub-frame being arranged for readily releasable attachment to the vehicle body so as to be carried on the vehicle body during operation of the vehicle and being removable from the vehicle with the engine components thereon for servicing of the engine components;
the sub-frame itself being incapable of supporting by itself at least one of the engine components;
and a movable service dolly for supporting during servicing the subframe with the engine components thereon, the dolly including:
first support elements for supporting the sub-frame;
and second support elements for supporting said at least one component such that the dolly and the sub-frame co-operate to support all of the engine components during servicing.
Preferably the engine component which is carried on the dolly during servicing and is attached to the body in use is attached to both the sub-frame and the vehicle body so as to receive support from both the sub-frame and the vehicle body in use. This ensures the proper location of the elements both during assembly and service on the dolly and when carried into installation in the vehicle body.
Preferably the second support elements on the dolly for supporting the component include adjustable jacks for adjusting the height of the component relative to the dolly. This allows the height to be adjusted as the sub-frame is brought into registration with the body to ensure that the connection to the body can be properly made before the dolly is withdrawn.
Preferably the dolly includes ground wheels by which the dolly can be rolled and wherein the vehicle body is arranged such that the dolly and the subframe with the engine components thereon can be rolled into one end of the body.
Preferably engine components include an engine, a radiator for cooling the engine, a transmission and connections therebetween such that the components are sufficiently complete to operate on the sub-frame and dolly during servicing.
Preferably the radiator is mounted on one side of the sub-frame for location in an opening at one side of the vehicle body and wherein the radiator is attached to the vehicle body at the opening. This ensures proper co-operation between the radiator and the body at the opening to prevent rattle and to hold the radiator properly aligned with the opening.
Preferably the sub-frame is arranged for insertion into the vehicle body from one end and wherein the transmission is mounted on a remote end of the subframe for insertion into the vehicle body beyond the engine and wherein a remote end of the transmission is mounted on the vehicle body.
Preferably the vehicle body includes two parallel longitudinal beams on which the sub-frame is carried and wherein each beam includes an inwardly projecting tab member onto which a mounting of the remote end of the transmission is located. This allows the dolly to be located between the main beams and moved into place without the dolly contacting or interfering with the main beams as the components are transferred from the dolly to the main frame.
Preferably the engine components and the sub-frame are located at a rear end of the vehicle and the transmission is arranged to drive a differential of a rear axle of the vehicle. This is a convenient and common arrangement suitable for transit vehicles but the same concepts can be used for a front mounted engine or in other types of vehicle.
Preferably the dolly is arranged such that the engine components when supported on the dolly are at a height greater than when supported on the vehicle body. This allows the engine components to be at a height convenient for servicing and to allow them to be wheeled into the engine bay of the vehicle with the vehicle raised or jacked to a convenient height to allow an operator to enter the bay to make the necessary connections
Preferably the sub-frame is arranged for mounting on the vehicle body at one end of the vehicle body and wherein the sub-frame includes bumper plates at an outer end for carrying a bumper of the vehicle.
The above dolly and sub-frame arrangement can be used either with conventional engine and transmission arrangements, where the transmission is mechanical and/or hydraulic or with other arrangements such as so-called hybrid drive systems where in a series hybrid system the conventional mechanical transmission is replaced by an electrical generator driven by the engine and a motor driven by electrical power from the generator and in a parallel hybrid system the conventional mechanical transmission is replaced by a transmission system which allows supply of power from or to an electric motor/generator.